1. Field of the Invention
This present invention relates to a digital zooming apparatus. More specifically, this invention is related to a digital zooming apparatus for adjusting the size of a sensed image sensed by a sensor.
2. Description of the Prior Art
No matter in digital or traditional cameras, an optical viewfinder is generally used for capturing an image relative to the real scene and for providing the captured image as a reference to users. The image captured by an optical viewfinder enables users to know more accurately what scene is going to be taken as photos. To adjust the range of scenes to be taken, most cameras has zooming functions. Some digital cameras have optical and digital zooming functions at the same time.
Optical zooming is adjusting a zoom lens manually or mechanically. Manually zooming is moving the zoom lens by a user's hands. Mechanically zooming is expanding or contracting the zoom lens with a driving device, for instance, a motor. Both manually and mechanically zooming adjusts the focal length of cameras via changing the position of a zoom lens.
Generally speaking, digital zooming in digital cameras is performed by first temporarily storing an image sensed by a sensor in a memory space. The sensed image is then resized by an image processing unit. When designing the hardware of a digital zooming apparatus, the storage capacity of a memory has to be considered. If the designer wants to completely store the sensed image into the memory at a time, the storage capacity of the memory then has to be large enough and the cost is high. On the contrary, if the memory is designed to have a smaller storage capacity, the sensed image must be partially stored in to the memory for several times. The image processing unit then synchronously resizes the part of the sensed image stored in the memory. If the efficiency of the image processing unit is lower than the speed of storing the sensed image into the memory, some image data might be lost.
Accordingly, one object of this invention is providing a digital zooming apparatus to overcome the aforementioned problems.